On a rifle range or pistol range, knowledge of the accuracy of a rifle, shotgun or pistol is necessary if a shooter is to determine where to aim to hit a target (or to group shot on a target in the case of a shotgun). Acquiring that knowledge has been a problem for many years. All manufacturers of firearms perform some sighting-in of the guns they manufacture, but each owner of a gun has to work out, independently, how to aim the gun to have the best chance of success.
In the specification of Australian patent application No. 15404/02, entitled “Apparatus and method for calculating aiming point information for rifle scopes”, the factors that contribute to inaccuracy in aiming a gun are outlined. The proposals for improving aiming that are found in the specifications of U.S. Pat. No. 1,190,121 (to Critchett), U.S. Pat. No. 3,948,587 (to Rubbert), U.S. Pat. No. 3,492,733 (to Leatherwood) and U.S. Pat. No. 4,403,421 (to Shepherd) are discussed and the reasons for the failure of those proposals are noted. After this discussion, a reticule for a telescopic gun sight which can be calibrated automatically by using a hand-held electronic ballistics calculator is described. The hand-held electronic ballistics calculator is a computer containing a ballistics program which uses data (including some or all of temperature, wind speed and wind direction, barometric pressure, relative humidity and the slope of the ground over which a bullet will be fired) to align the novel reticule for accurate marksmanship. When the result of the aiming of the rifle is known, the ballistics calculator indicates the changes in the set-up parameters that are needed to improve the aiming of the rifle.
The device of patent application No. 15404/02, however, appears to be designed for use by hunters, who need to shoot over long distances. In addition, the setting up of the device requires knowledge that is often not available, and the parameters selected (especially wind speed and wind direction) can vary significantly in a very short time.